Abstract: A machining fixture contains: a base, a plurality of positioning blocks, and a workpiece holder. The base includes a first connecting face on which plural fixing slots are arranged, and each fixing slot has a threaded hole. Each positioning block includes an affix portion and a fixation portion having two symmetrical contacting faces and two flexible portions. Each positioning block further includes a mounting hole or blind aperture defined on a middle section thereof and passing through the affix portion from the fixation portion. A screw bolt is screwed with the threaded hole of each fixing slot via the a mounting hole or blind aperture, and the affix portion of each positioning block enters into and contacts with each fixing slot of the base. The workpiece holder includes a second connecting face on which plural locating slots are arranged.

Abstract: A machining fixture contains: a base, a plurality of positioning blocks, and a workpiece holder. The base includes a first connecting face on which plural fixing slots are arranged, and each fixing slot has a threaded hole. Each positioning block includes an affix portion and a fixation portion having two symmetrical contacting faces and two flexible portions. Each positioning block further includes a dead aperture defined on a middle section thereof and passing through the affix portion from the fixation portion. A screw bolt is screwed with the threaded hole of each fixing slot via the dead aperture, and the affix portion of each positioning block enters into and contacts with each fixing slot of the base. The workpiece holder includes a second connecting face on which plural locating slots are arranged.

Abstract: A biosynthesis method of norephedrine with specific optical activities is revealed to convert and generate optical isomers with specific optical activities by biocatalysis. A two-step biotransformation reaction is carried by a whole-cell biocatalyst for converting reaction substrates, benzaldehyde and pyruvate, to L-phenylacetylcarbinol (L-PAC) in the first step and the yield of the L-PAC is 99%, and then an amino donor (L-alanine) is added and the transamination of the L-PAC is catalyzed by a transaminase with optical specificity for biosynthesizing the norephedrine with high optical purity. The pyruvate is produced from the amino donor, L-alanine, by the transamination in the reaction system, so that the pyruvate is regenerated in the reaction system without being added again.